Molded explosive bodies having variable detonation speeds

ABSTRACT

Process of manufacturing molded explosive bodies so that their detonation speeds can be varied within a defined range by reducing the density of the molded body. The reduction in density can be effected by incorporating into the starting components, porous, voluminous or air-containing materials. The solidification of the resulting compositions is thereafter carried out by incorporating into the above starting components a suitable binding agent, varying the working pressure in the forming of the bodies, or suitably regulating the sintering conditions. The resultant bodies are characterized by their reduced densities and therewith reduced detonation speeds and by their high-mechanical strengths.

iiiiiied tats aieni [72] Inventors Adolf lBerthmann Leveriiusen; Gerhard Martin, Troisdorf; Maximilian iflunsch, Opladen, all of Germany [21] Appl. No, 759,501 [22] Filed Sept. 12, 1968 [45] Patented Nov. 9, 1971 [73] Assignee Dynamit Nobel Aktiengesellschait Troisdorf, Germany [32] Priority Sept. 13, 1967 [33] Germany [31] ID 54099 [54] MOLDED EXPLOSIVE BODIES HAVING VARIABLE DETONATION SPEEDS 6 Claims, N0 Drawings [52] U.S.Cl 149/18, 149/46,149/60, 149/92, 149/93, 149/105, 264/3, 149/2, 149/21 [51] Int. Cl F42b H00 [50] lField oi Search 149/2, 17, 18, 19, 46, 21, 60, 55, 56, 57, 88, 93, 92, 105; 264/3 [56] References Cited UNITED STATES PATENTS 1,709,498 4/1929 Sorenson 149/2 X Primary Examiner-Benjamin R. Padgett Assistant Examiner-Stephen J. Lechert, .lr. Attorney-Burgess, Dinklage & Sprung ABSTRACT: Process of manufacturing molded explosive bodies so that their detonation speeds can be varied within a defined range by reducing the density of the molded body. The reduction in density can be effected by incorporating into the starting components, porous, voluminous or air-containing materials. The solidification of the. resulting compositions is thereafter carried out by incorporating into the above starting components a suitable binding agent, varying the working pressure in the forming of the bodies, or suitably regulating the sintering conditions.

The resultant bodies are characterized by their reduced densities and therewith reduced detonation speeds and by their high-mechanical strengths.

lVllOlLlDlEl) lEXlPlLOSllVlE BODIES HAVING VARIABLE DETONATKON SPEEDS This invention relates to molded explosive bodies having variable detonation speeds within a defined range. More particularly this invention relates to homogeneous explosive bodies with high mechanical strengths molded in any desired shape having detonation speeds which can be adjusted as desired to values of between 1500 m./s. and the maximum detonation speed of the specific explosive composition involved.

It is known that the detonation speed of explosives can be decreased by the addition thereto of inert substances. This procedure has only limited application, since the explosives sensitivity is so greatly diminished by very large additions of inert substances that the same are no longer capable of detonation.

Another possibility proposed for reducing the detonation speed is the reduction of the density of the explosive body by inclusion therein ofair spaces. This is accomplished, for example, by compressing the explosives at different pressures. The compression effects a reduction of the density, but at the same time it produces a diminution of the mechanical strength of the resultant body, so that the density can be reduced in this manner only down to a certain limit. This in itself constitutes a considerable disadvantage.

It is an object of the invention to provide molded explosive bodies having reduced densities and therewith reduced detonation speeds.

Another object of the invention is to provide molded explosive bodies having reduced densities and therewith reduced detonation speeds characterized by high mechanical strengths.

A further object of the invention is to provide a process for producing molded homogeneous explosive bodies of the type described.

These and further objects of the invention are accomplished by sintering or binding with known binding agents explosive compositions, consisting of known solid explosives and aircontaining, porous or voluminous materials.

In accordance with the invention there are accordingly provided explosive molded bodies having variable detonation speeds within a defined range, which are characterized in that in addition to the explosive agents, they contain porous, voluminous or aircontaining materials.

The molded bodies according to the invention having the necessary strength characteristics and which are possessed of the required homogeneity can be prepared without the danger that the components of the mixture will separate out by heating a homogeneous mixture of the explosive and density reducing components to close to the melting point of the explosive component.

In the case of nonsinterable explosives, or if the sintering temperature required is too high, a suitable sintering temperature can be selected by the addition ofa sinterable substance that may also be of an explosive nature.

An alternate method for solidifying the molded bodies according to the invention consists in adding a hardenable plastic or adhesive to the mixture of explosive and density reducing components and allowing the resultant compositions to set rather than using the sintering process. In this case the manufacture of the molded bodies is carried out, for example, by uniformly mixing the porous, voluminous, or air-containing materials with a binding agent and the explosive in finely powdered form, it being desirable in this connection for the grain size of the explosive to equal the grain size of the other components, since otherwise the danger that the components will become separated in the mixture exists. The mixture is then put into a mold which is closed with a plunger and pressed. The pressure employed ranges preferably between 0.1 and l kg./cm. though it may be lower or higher. To achieve bodies of equal volume and hence of equal density, the movement of the plunger can be limited while the same quantity is always charged.

When the sintering process is used, in which case the addition of the binding agent can be omitted, i.e., the explosive itself serves as the binding agent, and then the filled molds are brought to a temperature just under the melting temperature of the explosive. The sintering temperature depends on the purity of the fusible explosive component used, or the melting point of the eutectic mixture if mixtures are used. The sintering temperature can also be raised albove the melting point if the percentage of the component or mixture thereof that is to be melted, (i.e., the amount of fusible mixture of explosive) is so low that no separation of the mixture takes place. The most important sintering explosive involved is trinitrotoluene (TNT). However, explosives or explosive mixtures can also be advantageously used which are still sufficiently stable at their melting temperature and which do not tend to undergo separation. The pressure in the sintering process amounts preferably to 0.1 to l kp./cm. though it may be higher or lower. After the mixture has set or cooled in the sintering process, the bodies, which until then have been kept under pressure, are removed from the mold.

The explosives which can be used according to the invention include, for example:

a. Aromatic nitro substances, such as trinitrobenzene,

trinitrotoluene, trinitroanisole, trinitrocresol, trinitrophenol (picric acid), trinitrophenetol, trinitroresorcionol, trinitromethylaniline,

trinitrophloroglucine, hexanitrodiphenylamine, (hexyl) hexanitrodiphenyl, hexanitrodiphenylsulfide, hexanitrodiphenylsulfone, hexanitroazobenzene.

b. Nitramines, such as cyclotrimethylenetrinitramine (hexogen), trinitrophenylmethylnitramine (tetryl), cyclotetramethylenetetranitramine (octogen ethylenedinitramine.

c. Nitrosamines, such as cyclotrimethylenetrinitrosaminc.

d. Nitric acid esters, such as pentaerythritol tetranitrate.

e. Ammonium nitrate admixed with a combustible substance.

As air-containing materials there come into consideration the materials which consist of individual gas-filled hollow bodies, such as microbubbles (hollow spheres of phenolic or urea resin), and closed-pore foam plastic.

As porous materials there are intended the substances which are filled with fine airspaces, but whose openings to the surface of the particles are nevertheless so small that viscous liquids (for instance, adhesives cannot appreciably penetrate therein.

As voluminous materials there are suitable those substances having a large surface area and a low bulk weight, as for example, wood flour and cork flour.

The binding agents which are suitable for use herein include:

a. Adhesives dissolved in water or an organic solvent, whereby the setting takes place by the evaporation of the solvent, including glue, dextrine, polychlorobutadiene, polyvinyl acetate, and other like compounds.

b. Inorganic binding agents to which water is added and which set as a result of the addition of water, for instance, plaster of Paris, Portland cement, magnesium cement, minium-glycerin cement, and other like mixtures.

The explosive molded bodies obtained by the process of the invention have such great strength that they can after their production be subjected to mechanical working.

By combining molded explosive bodies having different detonation speeds, systems can be formed which form a shock wave front of any desired shape when they are detonated.

The invention is illustrated by the following examples. The same are, however, not to be construed in limitation thereof.

The percentage of air-containing materials and/or porous materials and/or voluminous materials in the molded explosive bodies is 0,1 to 40 percent, preferably 1 to 30 percent based on the explosive composition.

The binding agents cited sub 0) are used in an amount of 2 to 40 percent, preferably 5 to 25 percent based on the explosive composition.

The binding agents cited sub b) are used in an amount of 4 TABLE 1 to 35 percent, preferably 10 to 25 percent based on the explosive composition.

Example 5 6 7 EXAMPLES 1-4 5 Ammonium nitrate (wt-q 85 77 74 Examples l-4 describe the manufacture of molded explo- 'f -8 14 13 sive bodies using the sintering method which has been set out r fgg gj iijxgf" 5 9 above, in which the explosive itself serves as the binding agent. 10 Vegetable not" wt-m l3 Trinitrotoluene was used as the explosive. Microbubbles havy. el 0.8 0.85 H ing a diameter of 0.005 to 0.15 mm. and prepared from f 'f pressufc' henolic resin were used to red e the d 't It t' swarms m no 80 a0 80 p uc ens] or erna Ive- Sintering time, hours 6 6 ly cork flour was used for this purpose. Detonation speed, m./s. 2.350 2.290 3.670

The quantities of the components which were used in each 1 5 TABLE III Examples 8 9 11 12 13 14 15 16 17 18 19 20 Nitropenta (Wt. percent)- 76 72 56 90 85 75 63. 2 56. 6 81 81 60 65 60 Microbubbles (wt. percent). 4 15 3. 4 i0 10 10 20 15 20 Centralit I (wt. percent).. 10 Araldit (Wt. percent) Adhesin R (wt. percent)... 33. 4 3.5. 4 Pattex R (wt. percent) 9 UHU R (wt. percent) Plaster of paris (wt. percent) Portland cement (wt. percent) Water added per 100 g. of mixture (cmfi) Density, gJcm. 0. 87 0.78 0. 68 0. 62 Compression pressure, kp./cm. 0. i 0. 1 0. 1 0. 2 sintering temp., C 86 sintering time, hours 5 Detonation speed, m./s 4, 710 4, 280 3, 220 4,186

IIIIIIIIIIIIIII "9:11:

R Registered trademark. Notes: Centralit I= Dlethyldiphenyl urea.

Ara1dit=Synthetlc glue made from ethoxylin resins (cold setting twocomponent plastic).

Adhesin=Polyvinyl acetate.

Pattex=Contact cement made from polychlorobutadienc plus resins and organic solvents.

UHU=All-purpose cement (polyvinyl resin plus solvent).

case, the conditions of manufacture and the detonation speeds, are set out in the following table:

TABLE I Example I 2 3 4 TNT, ground (wt.-%) I00 89 73 90 Microbubbles (wt.-%) 0 ii 27 Cork flour 5 (wt.-%) [0 0 Density, g./cm. 1.1 0.74 0.4 0.3 Sintering pressure (kpJcm!) 0.5 0.2 0.4 0.3 Sintering temp. in "C. 79 79 79 80 Sintering time, hours 5 S 5 5 Detonation speed, m./s. 5,700 3,360 1,500 2,710

EXAMPLES 5-7 EXAMPLES 8-20 Examples 8-10 and 14-20 describe the manufacture of the molded explosive bodies using a binding agent which sets without heating. Such agents include adhesives sold under the trade names Araldit, Adhesin," Pattex and UHU," as well a plaster of Paris and Portland cement. (The trade names are more precisely defined in the following summary.)

Examples 1 l-l3 are specifically concerned with the manufacture of the molded explosive bodies using the sintering process, in which an inert compound without properties of an explosive serves as the binding agent.

The quantities of the components, the manufacturing conditions as used in examples 820, and the detonation speeds are reported in the following table. The microbubbles which have been used are the same as those which were used in examples -.4

We claim:

1. A process of manufacturing a homogeneous, high strength, molded explosive body having a predetermined detonation speed comprising admixing particles of a meltable explosive and of a density reducing material in proportions to give said detonation speed, sintering the admixture by heating the same while confined in a mold form to a temperature close to but below the melting temperature of that component of said meltable explosive having the lowest melting point, cooling the thus heated admixture and removing it from said mold form, said meltable explosive being selected from the group consisting of aromatic nitro compounds, nitraamines, nitrosamines, nitric acid esters and ammonium nitrate, and said density reducing material consisting of a finely porous, voluminous inert ingredient having a large surface area and a low-bulk weight.

2. The process of claim 1 wherein said meltable explosive is trinitrotoluenev 3. A homogeneous, high strength, molded, explosive body having a predetermined detonation speed comprising a sintered mixture of particles ofa meltable explosive and ofa density reducing material, said meltable explosive being selected from the group consisting of aromatic nitro compounds, nitraamines, nitrosamines, nitric acid esters and ammonia nitrate and said density reducing material consisting of a finely porous, voluminous, inert ingredient having a large surface area and low-bulk weight.

4. A homogeneous high strength molded explosive body according to claim 3 wherein said meltable explosive is trinitrotoluene and said density reducing material are hollow spheres of phenolic resin.

5. A homogeneous high strength molded explosive body according to claim 3 wherein said meltable explosive is trinitrotoluene and said density reducing material is cork flour.

6. A homogeneous high strength molded explosive body according to claim 3 wherein said explosive component comprises a mixture of ammonium nitrate and trinitrotoluene and said density reducing material is a member selected from the group consisting of hollow spheres of phenolic resin, wood flour and vegetable flour.

g gg UNlTED s'm'ms PATENT OFFICE y CERTIFICATE OF CORRECTION Patent No. 3,619,306 Dated 1971 Inventor) ADOLF BERTHMANN, GERHARD MARTIN and MAXIMILIAN *IGIUNS'GH It is certified that error appears in tho above-identified patent and that said Letters Patent are hereby corrected as shown below:

[ Col. 3-4, in Table III, 2nd item undgr .the heading "1]."

"6" should be --5-- Signed and sealed this 20th day of June 1972.

(SEAL) Attest:

EH IARD M.FLEI'CHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

2. The process of claim 1 wherein said meltable explosive is trinitrotoluene.
 3. A homogeneous, high strength, molded, explosive body having a predetermined detonation speed comprising a sintered mixture of particles of a meltable explosive and of a density reducing material, said meltable explosive being selected from the group consisting of aromatic nitro compounds, nitraamines, nitrosamines, nitric acid esters and ammonia nitrate and said density reducing material consisting of a finely porous, voluminous, inert ingredient having a large surface area and low-bulk weight.
 4. A homogeneous high strength molded explosive body according to claim 3 wherein said meltable explosive is trinitrotoluene and said density reducing material are hollow spheres of phenolic resin.
 5. A homogeneous high strength molded explosive body according to claim 3 wherein said meltable explosive is trinitrotoluene and said density reducing material is cork flour.
 6. A homogeneous high strength molded explosive body according to claim 3 wherein said explosive component comprises a mixture of ammonium nitrate and trinitrotoluene and said density reducing material is a member selected from the group consisting of hollow spheres of phenolic resin, wood flour and vegetable flour. 